The Fairfax County Fire and Rescue Department determined the fire was set accidentally while a contractor was using an open-flame torch to repair a leak in the roof of the building. The fire also spread to the outer wall.

“It took 20 minutes to bring the fire under control,” said Dan Schmidt, public information officer for Fairfax County Fire and Rescue. Schmidt said fire and water damage were estimated at about $40,000.

Fairfax County FCU reopened its headquarters and main branch on a normal schedule Friday. Phone and online services were expected to be restored some time during the day, according to the credit union’s prepared statement.

“We’d like to express our sincere appreciation to the men and women of Fairfax County Fire and Rescue Department as well as the Fairfax County Police Department for their tremendous efforts in protecting the lives of those in the building and the building itself,” Joe Thomas, president/CEO of Fairfax County FCU, said in the statement.